Ryanair has apologised after a number of passengers complained cheques issued as compensation had bounced.

The airline said “a very small number of cheques” processed in July had been issued without a signature due to an “administrative error”.

Consumer complaints service Resolver said it was aware a number of Ryanair passengers had encountered problems with unsigned cheques issued when flights had been delayed or cancelled.

The admission comes after the airline had to cancel flights due to striking Irish pilots last month.

Ryanair said the cheques had been reissued to customers with a letter of explanation on 15 August.

“We apologise again for any inconvenience caused to customers,” the airline told the BBC.

A number of passengers complained they had been delayed in receiving compensation because their cheques had failed to clear.

One wrote on Twitter on 14 August: “@Ryanair I have been trying to get hold of someone urgently as my bank are concerned because a compensation cheque that I received has bounced, i think that this is outrageous, the bank said the bank details provided do not exist...how is this possible with a printed cheque....”

Another passenger wrote on Facebook on 28 July: “Ryanair sent me a cheque for compensation then BOUNCED the cheque..ended up costing me 32 eu (£29) for the privilege. SHAME ON YOU RYANAIR. won’t respond to EMAILS and OPERATOR just put the phone down on me”.

Another passenger tweeted on August 9: “@Ryanair I would love to know why the cheque you sent me for compensation has bounced... Bank assure me this is your fault, wait 1 hour 20 on hold and your “customer services” cant help and there is no number to call to those who can? Please assure me of a call to fix this asap.”

The passenger said they were still waiting for the money 11 days later, writing to the airline: “Have contacted your call centre numerous times and just get a generic email saying my case is being delayed because I am obviously not the only person waiting for over a month for compensation...”

A strike by Irish Ryanair pilots in July saw up to 30 flights cancelled, affecting some 5,000 passengers.

The airline told the BBC: “Ryanair complies fully with EU261 legislation, under which no compensation is payable to customers when the (strike) delay/cancellation is beyond the airline’s control.